And more bureaucratic red tape, environmental constraints, tree huggers and so on. What a shame that USA can't have a "world class" rail passenger system, such as many countries in Europe and Asia.
It does not make sense to blame environmental protection for the US having bad train service. European environmental groups are stronger -- look how many seats their green parties have in different parliaments. Yes, environmental concerns block or raise the price of a particular project here and there, but that's not why we don't have good trains. Our environmental rules and environmental groups (even those you dismiss as tree-huggers) are just as likely to get in the way of any given highway project -- actually more so, because highway projects take more space and at least some environmentalists want to reduce the use of cars. US environmental groups are also one of the strongest voices in the country for better trains. Think of the Conservation Law Foundation trying to get the North-South Rail Link, the Arboway Line, and the Red-Blue connector built in Boston.
I would have a different list of reasons for the difference: Americans act as if driving is a right and building any number of roads is a necessity, and treat flying similarly, but they treat taking trains, buses, streetcars, and other mass transportation as a frill and treat building mass transportation infrastructure as an option. Put another way, a majority of Americans assume that roads and highways are a public proposition of general interest and that gas taxes should be so low that cities and states have to use regular tax revenue to cover most streets and non-interstate roads, while mass transit is special interest proposition that is grudgingly subsidized with lots of complaints that it doesn't make a profit (as if the highways and streets made a profit!). Our laws make it much easier to get big highway projects funded than to get big rail or transit projects funding, and the feds pay a bigger share of highway projects in general.
As a result, we have bad passenger rail and mass transit systems, which in turn encourages more people to think of driving as normal and trains as outmoded, which in turn leads to politics continuing to favor roads over rail.
European countries treat rail as a sensible way for everyone to get around, and most people use it. They fund rail accordingly. Sure, they also build roads, but the balance is more even. To be fair, they also have a lot more dense regions where rail service makes sense, or maybe I mean fewer big empty regions where it's hard to justify a train (there's no Nebraska or Wyoming in Europe, not even in Scandinavia or European Russia).